Combine flour, salt and pepper in a plastic or paper bag. Add chicken in batches to bag; shake to coat lightly with flour.
Melt butter in a large nonstick skillet over medium heat. Add chicken to skillet; sauté 4 to 5 minutes per side or until chicken is cooked through. Transfer chicken to a serving platter; tent with foil and keep warm.
Add mushrooms and garlic to same skillet; sauté 4 minutes. Add wine and broth to skillet; simmer 3 minutes. Stir in pepperoni; simmer 3 minutes or until sauce is slightly thickened.
Spoon sauce over chicken; garnish with parsley.